1. The Field of the Invention
The present invention is in the field of graft tensioning devices used in joint repair surgery, such as reconstruction of the anterior cruciate ligament (ACL). More particularly, the invention relates to suture separation and organization devices for use with graft tensioning devices.
2. The Relevant Technology
Graft tension in ACL reconstruction is recognized as an important factor in the clinical outcome of the ACL reconstruction procedure. Grafts that are too loose may be unstable, and grafts that are too tight may greatly restrict motion of the knee. Publications that have emphasized the need for adequate tensioning of the graft include Markolf et al., “Biomechanical Consequences of Replacement of the Anterior Cruciate Ligament With a Patellar Ligament Allograft. Part Two: Forces in the Graft Compared with Forces in the Intact Ligament,” J. Bone Joint Surg. Am., 78:11, 1728-34 (November 1996); Tohyama et al., “Significance of Graft Tension in Anterior Cruciate Ligament Reconstruction. Basic background and clinical outcome,” Knee Surg Sports Traumatol. Arthroscopy, 6 Suppl. 1, S30-7 (1998); Andersen et al., “Review on Tension in the Natural and Reconstructed Anterior Cruciate Ligament,” Knee Surg. Sports Traumatol. Arthroscopy, 2:4, 192-202 (1994); Yasuda et al., “Effects of Initial Graft Tension on Clinical Outcome After Anterior Cruciate Ligament Reconstruction. Autogenous Doubled Hamstring Tendons Connected in Series of Polyester Tapes,” Am. J. Sports Med., 25:1, 99-106 (January 1997). The foregoing publications are incorporated herein by reference.
Devices used to apply a known load to a soft tissue graft are set forth in U.S. Pat. No. 4,712,542; U.S. Pat. No. 5,037,426; U.S. Pat. No. Re 34,762; U.S. Pat. No. 5,713,897; U.S. Pat. No. 5,507,750; and U.S. Pat. No. 5,562,668. For purposes of disclosing mechanisms for applying a known load or tension onto a soft tissue graft, the foregoing patents are incorporated herein by reference.
A study by Hamner et al. has added to the understanding of graft tension by demonstrating that unequal tension in the individual strands of the soft tissue graft can result in significant losses in total graft strength and stiffness. Hamner et al., “Hamstring Tendon Grafts for Reconstruction of the Anterior Cruciate Ligament: Biomechanical Evaluation of the Use of Multiple Strands and Tensioning Techniques,” J. Bone Joint Surg. Am., 81:4, 549-57 (April 1999). Hamner et al. found that tensioning the soft tissue strands by hand would result in equalization of the load borne by each strand, and that this method was not effective in equalizing the load on the strands, which led to an ultimate graft strength that was not significantly greater than the strength of the individual strands taken alone.
Apparatus and methods for separately applying a load to and conditioning different strands of a multiple-strand soft tissue graft are disclosed in U.S. application Ser. No. 09/711,488, filed Nov. 13, 2000 in the name of Hugh S. West, Jr. and John R. West and entitled “Apparatus and Methods for Independently Conditioning and Pretensioning a Plurality of Ligament Grafts During Joint Repair Surgery”. For purposes of disclosure, the foregoing application is incorporated by reference. The apparatus and methods disclosed in the foregoing application represent a major breakthrough in joint repair apparatus and techniques.
Notwithstanding the foregoing, there is a continuous need to find improvements to apparatus and methods used during joint repair surgery, particularly in organizing individual suture strands that are attached to a soft tissue graft.